Portion of a dental floss device



FIG. 1 is a perspective view of the portion of the dental floss device embodying the new design;

FIG. 2 is a front view thereof; and,

FIG. 3 is a right side view thereof.

FIGS. 1-3 show portions of the design in broken lines. The portions shown in broken lines form no part of the claimed design. 

CLAIM The ornamental design for a portion of a dental floss device, as shown and described. 